Carbon Sequestration in Flood Basalts: An Overlooked Sequestration Option

B. Peter McGrail¹, H. Todd Schaef¹, Stephen P. Reidel¹, and James J. Dooley^2
1 Pacific Northwest National Laboratory, Richland, WA
² Joint Global Climate Research Institute, College Park,

Flood basalts are an overlooked but potentially important host medium for geologic sequestration of anthropogenic CO_2.  Most lava flows have flow tops that are porous, permeable, and have enormous capacity for storage of CO₂.  Major flood basalts exist in the U.S. and India.  Approximately 25% of India's current coal-fueled power plants are located on or in close proximity to the Deccan Traps.  In the U.S., over $400M has been invested in characterizing flood basalts in the Pacific Northwest that provides a unique geological database from which to assess the potential of basalt flows for carbon sequestration.  For the Columbia River Basalt Group alone, conservative estimates of storage capacity are in excess of 100 GtCO₂.  Laboratory experiments confirm rapid chemical reaction of CO₂-saturated pore water with basalts to form stable carbonate minerals.  Supercomputer simulations of CO₂ injections on the scale of about 100 km² show that dense low-permeability basalt rock overlying sequential flows act as effective seals allowing time for the mineralization reactions to occur.  Mineralization rates actually may be controlled by hydrodynamic mixing processes in vesicular basalts, not the kinetics of rock-water reactions.  Preliminary studies shows that several already existing boreholes located on the Hanford site in Washington State could be used for CO₂ injections to validate the laboratory findings on mineralization and CO₂ containment in a field setting.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005